An upcoming study looks to understand if epileptic seizure sufferers – especially those for whom previous medications have failed – can find much-needed relief by adding cannabis oil to their regular medication routine.
“Marijuana’s two main ingredients – cannabidiol (CBD) and tetrahydrocannabinol (THC) – have shown some promise in pre-clinical and early clinical studies to be effective in epilepsy,” explained Schulich School of Medicine & Dentistry professor Seyed Mirsattari.
And with the legalization of cannabis in October, Mirsattari stressed that clinical data on effective dosing, safety and long-term benefits of the product are in high demand.
In a Health Canada-approved study, researchers will assess whether CBD, plus a low dose of THC, decrease the number of motor seizures in adults with drug-resistant epilepsy, when that combo is used in combination with other anti-epileptic drugs.
THC and CBD are found naturally in the resin of the cannabis plant. THC is the psychoactive compound – responsible for the ‘high’ people feel – while CBD is not psychoactive and thought to be responsible for many of the medical benefits associated with cannabis.
Participants in the study will receive pharmaceutical grade cannabis oil capsules, supplied through Alberta-based Aurora Cannabis, at a CBD-to-THC ratio of 16:1, in addition to their regular medication routine.
In previous studies, high levels of THC had mixed results, including causing psychoses, especially in children, and provoking and/or worsening seizures in some patients. This current study looks only at adults.
“These are people who have what we call drug-resistant epilepsy where at least two seizure medications have failed on their current therapy,” said Mirsattari, who will also explore if any form of epilepsy may respond better to this treatment. “You don’t replace the old drugs; you add onto them. The idea is not to change a patient’s current maintenance, but to look at the effect after the new drug is introduced.”
A total of 80 participants – 40 assigned to treatment, 40 to a control group – are being recruited for the two-year study from Toronto Western Hospital and University Hospital in London.
When used as an add-on therapy, CBD oil has been shown to reduce the frequency of convulsive seizures in children and adults with Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis complex. People living with these forms of epilepsy have seizures that do not respond to medication, leading to long-term health risks including cognitive, behavioural and intellectual impairments.
Mirsattari said the chance is low for those who have failed two seizure medications to suddenly become seizure free. However, the possibility of reducing them by half is significant.
Mirsattari said this study will be an opportunity to learn more about how specifically CBD oil affects the immune system in reducing the number of seizures, something researchers are still puzzled about.
EpLink, the epilepsy research program of the Ontario Brain Institute, initiated a clinical study in partnership with Mirsattari and London Health Sciences Centre, along with Toronto Western Hospital neurologist Peter Tai and EpLink Co-director W. McIntyre Burnham.